Pavement and process of making same.



A. B. OOWDERY. PAVEMENT AND PROCESS OF MAKING SAME.

APPLICATION FILED 13110.7, 1909.

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A. B. GOWDERY.

PAVEMENT AND PROCESS OF MAKING SAME.

APPLICATION FILED DBO. 7, 1909.

Patented Apr. 15, 1913.

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ARTHUR B. COWDEEY, 013 BOSTON, MASSACHUSETTS, ASSIGNOR T0 BARRETT MANTL FACTURING- COMPANY, OF NEW YORK, .N. Y., A CORPORATION OF WEST VIRGINIA.

PAVEMENT AND PROCESS MAKING SAME.

Specification of Letters Patent.

Patented Apr. 15,1913.

Application filed December 7, 1909. Serial No. 531,827.

lopavements and the method of'constructinp the same.

It is one object of the invention to provide a process for making a firm and durable road at a reduced cost for materials and It is another object to make a pavement which combines with these qualities of firmness and durability a capability of being; repaired efiectively by replacement of only a 0 minor portion of its thickness.

To this end the invention provides improved and inexpensive means for sealing the'under part of the pavement tight against Water and air.

It has heretofore been proposed to lay roads in which the foundation consists of broken stones having their voids filled, either with broken stones, or like material, of smaller size, or else with cement or bituminous material. Such filling involves expense,

both for the filling material and for the labor of applying it, whether it be worked in with brushes from the top or wheth r it be mixed with the stones in advance; and in the latter case there is usually additional expense for heating; or drying the stones before the mixing occurs, if the material be bituminous; while, if the material be cement it cannot be rolled without being cracked, which entails admission of water and air and leads to an early disruption of the pavement.

By the invention herein described, a sub stantial part of the labor heretofore involved in' making pavement is saved; and also a substantial part of the material with which the voids between the stones have heretofore been tilled. At the same time a firm foundation is created. and perfectly sealed by a tough and durable upper structure. These objects are accomplished by forming the pavement, except the wearing surface, of

rather coarse broken stone in which the lower portion, for example the lower twothirds, is rolled firmand is left with its voids unfilled, and the upper portion has its voids filled, preferably with bituminous material, and a zone exists between these two portions which is filled with sand upon which alayer of bituminous material has been placed, 'which bituminous material works downward somewhatinto the sand and upward. somewhat about the stones in the upper portion. The voids of the upper portion are filled by grouting the bituminous material into them. The under sides of the stones in this upper portion are bedded in the bitu- I minous material which was placed on the sand and project downward into thetop voids of the lower portion, interlocking therewith. The sand forms a bottom for the grouting,preventing it from descending into the voids of the lower portion, so that grouting is needed only to fill the upper portion.

Further features or advantages appear in the detailed description which follows, ref-- erence being had to the accompanying drawings in which,

Figure lrepresents a stage in the making of the pavement; Fig. 2 a later stage showing the result of rolling; and Fig. 3 the finished pavement, being a still later stage.

In the drawings the various parts hereinafter described are indicated by reference numerals, as follows: The subterrane is marked 10, the first layer of stones 11, the

sand 12, the layer of bituminous material thereon 13, the second layer of stones 14; the result of the mixture of layers 12 and 13 by the rolling process is marked 15, the grouting poured from above in the second layer of stones is iii-and the layer of small stones thereon 17 and the top of the wearingsurface consisting of bituminous material and sand mixed, l8. y

The method or process of making my improved pavement will be understood from a description of one embodiment of the invention, and it will, of course, be understood that the sizes and kinds of material may be varied, and that other variations may be made from the precise method and construction here specifically described, without departing from the scope of the invention or of the patent.

For ordinary purposes the entire pavement may be about six inches thick, substantially all of which is composed of coarse broken stone of uniformgrade, as below described.

ulfter excavating to the desired depth, which should in such a case be about six inches below the finished gradedesired, the subterrane should be rolled until there no depressions and then should be filled with about five inches oi": broken stone of such a size that it has passed through a ring tweand one half inches in diameter and has been retained upon a ring one and one qnarter inchesin diameter; and. these stones should then be heavily rolled and compressed until they are firm and present an even surface. On this a layer of sand should'be spread loosely, about two cubic yards to each hundred square yards or" surface; and, on the sand, liquid bituminous composition, at temperature of not less than 220 F. should be spread, a suitable amount being about one gallon to the square yard. Over this, more stones of the same size as be fore are spread, about two and one halt inches deep, and are rolled as firmly as possible. Fig. 1 represents the structure before this rolling and Fig. the structure afterward. In this rolling they sinlt to a thickness oi about two inches, and their under sides are driven down through the bituminous compo sition, and into and through the sand, and

into such top voids or openings as exists in the surface of the previously rolled stones, causing, the same time, some readjustment of said surface stones, by which some oi them tip upward and are forc d between the stones above them. At the smile time the bituminous matter laid upon the sand becomes forced into and mixed with the sand, to a degree, and both it and the sand are 45. forced into Whatever openings exist in the top of the mass of stones under them ,'or are opened therein by the heavy rolling above, until all such entrances to the Voids in the structure of stones below are plugged by the sand or by the mixture of sand and bituminous matter. At the same time, the bituminous matter, which, of course, thoroughly coats the bottom sides of the bottom stones do osited upbn it, is forced upward on all sicfes ofthose bottom stones, thus insuring a perfect bituminous envelop and seal. about the under portions of those stones. This coats and makes a firm setting in concrete for the under portions of these stones, which is a resultnever'before attained, so far as I am aware, by any process in which the main portionof the voids immediately under the wearing surface of the road is filled by i grouting bituminous material therein, as such material cools so rapidly in contact with cold stone that it loses its fluidity and does not penetrate the liner crevices nor the larger openings beneath to which they may lead; and of course, it does not at all reach the under sides of the bottom stones.

After the rolling last described, heated bituminous material is to be spread, (Fill-Yb tity of one and one quarter to one and a halt gallons to the square yard being approximately suitable, the quantity being sutlicient to fill all voids in the upper tvo inches of stone, in. so far as the voids therein have not been filled by the bituminous mate lid and sand rising from below during the rolling. As soon as possible, small sized broken stone 30 should then be spread, between three quarter and half inch size, a quantity of about no cubic yard to a hundred square yards bei P usually sufiicient, and the road should tlu be firmly rolled and t an swept cle n of dirt or particles of stone that may rcpwr. unbonded by the bituminous mu erial. Or. a this may be spread evenly additional layer of bituminous material, to the amount of about one half gallon per sqizare yard. and covered immediately with sharp coarse sand, after which the road may be rolled. again. and is ready for use. In the completed pavement there is thereforea Wearing surface consisting of bituminous material and sand and small stones which ls the pavement at the very top and be dud to the six inches or so of coarse stones and is, to a degree, embedded in the top ids thereof. The upper third of this sir: inches is of strong and sizable stones in Which-the voids are completely filled with bituminous material and the under sides of the stones iveloped and firmly bedded in bituminous u rial. Tl' s two-inch layer is mechanica ly i0?- locked. with the firm structure or similar stones beneath by the downward prey-acting? points of its lower stones and the ups-arc. projecting points of the upper stones of the said under portion. The zone of sand, inter vening where these two portions adjoin. served the function, during construction, of holding bituminous liquid upon Fill face until the upper stones were spread in it, thus coatingthe under sides thereof com" pletely, and of holding thebituminous mate rial further while itand the sand and the adjacent portions of stones above and below the sand were intermingled and kneaded. by the rolling, into a firm stable mess of concrete, supported on a structure of coarse stones with empty voids between them. This upper two inches as thus described, with the clam of sand and concrete under it is relied upon to exclude air and water from the 2%. voids below. As a preliminary matter, the foundation" should be subclrained if necessary, to keep Water from running into from the sides.

In a foundation thus constructed, the 136 further considerable saving in labor.

voids of the lower portion remaining unfilled, the costofmateria-ls to fill them is saved; and the cost or filling them, whether by preliminary mixing or by rubbing the filler in from the top, is saved. The rolling of the stones will naturally be such as to close the voids as much as possible, without rounding the stone, and if this be done the stones will lie in firm jointure, and will be as a mass, in stable equilibrium.

The top portion constitutes a perfect concrete and diilers from other concrete in that it is formed and kneaded in 552521 without preliminary mixing or heating of stones, and-by the very simple processes of spreading, of pouring, and of rolling. This is y the use of bituminous or asphaltic binder by this method it is possible to leave unfilled the voids of the greater part of the siX inches thickness of pavement, because such a binder is so elastic that itwill endure the greater degree of concussion and of variations of temperature and pressure which a superficial layer receives,. as compared with a solid layer from top to bottom; so that the filling from top to bottom which has hitherto been necessary where cement has been used is obviated.

In the same manner the pavement whose construction has been described allows for repairs of the top or: the road upon removal of about two inches. A. patch can then be ut on and willadhere to the existing ounation without necessity of removing the material to the very bottom in orderto get firm adhesion.

Ifit be desired to apply the invention to the improvement an existing road, the said existing road may in many cases be utilized as the lower element in the improved road, in place-of the bottom layer of broken stones with empty voids, as above described, in whichithe individual stones lie in whatever relatio Qoeach other they are thrown by chance A such cases the top of the existing road,"whi'eh may be any kind of a road'capable offurnishing a firm support for the sand and upper body, should first be washed or swept out to remove all dirt and then tlie'above described successive layers of sand, bituminous binder, coarse stone, grouting-,.and wearing surface may be applied. In some cases, particularly where the existing road has an asphaltio surface or other sort of fairly smooth surface without top voids, itmay be well to first coat such surface with some suitable material which will stick to it and to which the layer of sand will stick. Whenthe bitutures of the invent-ion. For these reasons mention of the finer materials added to finish the top of the pavement is omitted in the claims.

I claim 1. The method of constructing a pavement which comprises spreading a layerof coarse broken stone; rolling till firm; spreading sand or the like loosely on it; spreading thereon liquid bituminous binder; spreading upon that more broken stones; driving the latter stones down into inter locking relation with the first mentioned stones by rolling the whole; and grouting with liquid bituminous binder to fill the voids in the last applied stone.

2. The method, of constructing a pavement which comprises providing a firm under support; spreading sand or the like loosely thereon; spreading liquid bituminous binder on the sand; spreading coarse broken stones over said liquid; mixing the sand and binder into concrete and surrounding the under portions of said stones with suehconcrete by rolling said stones; and applyin a liquid grouting to fill the voids in sai stones.

3. A pavement comprising a body of stone broken coarsely in irregular shapes, the position of individuals in said body of stone being arranged by chance with projecting corners intervening between other stones in the body whereby a structure of interlocked individuals of approximately the same size is constituted; and said body having intermediate'of its height a layer of sand and bituminous binder mixed; the voids in the stones below the said sand layer being empty; and the stones above said sand layer being surrounded and their voids filled with bituminous binder supported on the sand.

4, A pavement formed in layers comprising coarse broken stone at the bottom with the voids therein empty; sand resting on said stone and filling the top voids thereof; bituminous binder supported on the sand; coarse broken stone thereon, having its under sides coated and its voids filled with bituminous binder supported by the sand layer; said coarse stones being broken in irregular shapes of approximately the same size and the individuals in the two layers interlocking with each other through the said intervening bituminous binder and sand.

5. A pavement-- formed in layers compris- 'ing a firm under-support having an irregular upper surface adapted to receive and finial-lock with atonea above it; a layer oi sand supported thereon; bituminsus binder retained by the sand; coars stones broken inks irregular individl xi shapes having projecting cm'nex's penetrating'ne binder and sand 211d interlocking with said support these stems having their under and voids fined with i sldes coated. 391 uminous smear rcialrm in pssiuon by sud Ewen 3-? "I 1 1 1 I lgzmn my ai- Bsston, Mass",

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